3/4/08 - You aren't imagining things - yes, there has been an update. I've replaced all PNG screenshots with JPEGs. They're about half the file size, and after doing a comparison in Photoshop, there's no difference in quality between the two.

Previously:

3/15/07 - A mod for mods! How to build a simple audio mixer for your AtariVox and a modified 2600.

8/7/04 - If this isn't a modded 2600, I don't know what is! Check out the page I've set up about my Imagic kiosk!

7/2/04 - It never ends... I added
test results for an adjusted CyberTech mod. Turns out the saturation
was turned up too high. While this may not cause everyone a problem,
it did on my TV, which I've detailed on
this page. I'm also working at getting a modded 2600 from
povlok1, and a 2600 Jr. to test, but that probably won't happen
until August.Finally,
I've added a page detailing my favorite
joystick modification. Check it out - I think it works great!

7/1/04 - Clarified a few notes regarding
contact cleaner, using a VCR to stabilize video, making audio
mods, video artifacts on screen captures, and making an S-Video
to composite adapter. Whew! (Thanks to Chris Wilkson, Dan Schmidt,
Bohus Blahut, Sku-u.)

6/21/04 - Completely re-did everything:
all of the tests, screen captures, results, etc. Added more pictures
(as if the page didn't take long enough to load before), added
CyberTech video mod info, added thumbnails for all screen captures
and added more (hopefully useful) links. Removed references to
the 7800, since I've decided to limit the scope of this page to
the 2600. Created a logo for the page. Sorry, T-shirts are not
available. ;)

6/1/03 - Had to remove 7800 RF adapter
images, due to a lack of server space.

Index:

About this project:

This site has been set up for the sake of
comparing the various video modifications that have been created
for the Atari 2600. Whether that means just building them from
schematics, or getting them in the form of a kit, the idea is
to give people an idea of what's involved with them, and more
to the point, how well each of them works.

Originally, I was hoping to create the elusive
"how-to" guide, but that's really not practical. If
you can solder and have a basic understanding of electronics,
you can install one of these yourself. At the very least, you
need to know how to solder. If you don't, you can usually find
some tips
online. You can get by with a pretty cheap, low-watt soldering
iron from Radio Shack. Just be sure to practice on something you
can live without, before going to work on your 2600.

I'm not trying to put down any of the people
who have developed these mods. Some work better than others, some
will suit some people's needs better than others. All of these
mods are available online either as plans or for purchase. I haven't
developed any of the mods on this site - they were all invented
by other people. I'm just testing them out as impartially as possible.

Finding the parts for these may or may not
be easy. Radio Shack carries precious few electronic components
anymore. I ordered most of the components for the video driver
and CD4050 mods through Nationwide
Electronics, Inc. The circuit boards, terminals and connectors
all came from Radio Shack. All parts for Ben Heckendorn's mod
came from Radio Shack, so that's a plus. Electronix
Express and Digi-Key
also carry most of this stuff, although NEI was the only place
that had the transistor used in the video driver mod. For wiring,
I used some spare category 5 cable (very easy stuff to work with).

The CyberTech mod is available through Atari2600.com.
You can purchase a kit to install yourself, or pay them to do
it. I have no idea what the shipping costs for sending a 2600
back and forth would be. There are no online plans to build one
of these yourself, and given the complexity of it, there are probably
few who would want to make the attempt.

The Color Bar Generator cart (originally
by VideoSoft) used in these tests is a copy that I ordered from
Hozer video. All of the rest of the carts are from my own collection.
Some of the games were chosen based on feedback in the AtariAge
Hardware forum.

All of these mods are tested using NTSC
consoles and video equipment. I don't have the facilities available
to test any PAL consoles or games. Sorry about that.

The mods:

I've tested the following video mods on
both a six-switch and four-switch Atari 2600 (some of these are
listed in the Atari
2600 FAQ). The Atari 2600 used for the screen captures is
the six-switch model (it's actually a Sears Video Arcade, but
it's always been "an Atari" to me). I didn't test any
mods in an Atari 2600jr., since I don't own one. With the exception
of the CyberTech mod (which comes pre-built), I built these based
on plans freely available on the internet.

RF options:

The Atari 2600 was originally designed to
output an RF modulated signal. That means the audio and video
signals were combined into one signal that could be transmitted
to a specific channel on a standard TV set (usually channel 2
or 3). This allowed the 2600 to be hooked up to any TV set at
the time, but generated visible noise in the picture.

To show the difference between RF and the
video mods, I also ran tests using RF through a standard switchbox
and a straight adapter (similar
to what AtariAge sells).

The dreaded switch box.
Dump it. If you can't dump it, blast some contact
cleaner in the switch.

..
A Female RCA to RF adapter (left) and an A/B switch (right) is
a much better solution.
Radio Shack even sells a remote-controlled switch, if you feel
like spending that much.

If you don't have an A/B switch, I'd suggest getting an RF push-on
adapter, to save wear and tear if you have to switch cables
a lot.

I also tried replacing the stock Atari RF
cable (below, left) with a good, shielded RF cable. It didn't
make any apparent difference, but your mileage may vary, depending
on the condition of your original cable. You'll need an adapter
like the one on the right to plug into the 2600's built-in RF
modulator, but you'll need to file the center post down, since
the original cable's is so much shorter.

If you don't file the post
down to match the plug on the left, the adapter won't fit the
2600's jack.

Other adapters:

I also tested two S-video to composite adapters,
for those who don't have an S-video input handy. The one on the
left is from Monster Cable, and costs about $100, although they
apparently don't make them anymore. That doesn't matter, since
the
one on the right costs about $5, and works just as well. There
are also instructions
on this page, for making your own adapter (although I haven't
tested it, the principle is the same as the store-bought adapters).

..

Something else you may want, is an RCA
"Y" adapter. Most of the mods just have one channel
of audio. If you're running it into a stereo TV, and want sound
to come out of both channels, you'll need one of these (although
the sound will still be mono).

If you get the CyberTech S-Video mod, you
may also want to pick up some female to female couplers. The cables
included with that mod are very short, and these allow you to
connect to longer cables.

Finally, if you need a something to switch
between different game consoles, I highly recommend Pelican's
System Selector. It's similar to most other switches you can find
at TV stores, except it costs only $20 (most other switches are
$30 - $40), it has five sets of inputs while most others only
have four, and it has interchangeable nameplates for the inputs
(except none that say "Atari"... for shame!).

..Pelican's System Selector
- front and back. It handles S-Video or Composite video, and can
pass cable through to your TV.

Building the projects:

Except for the CyberTech mod, the better
they work, the harder they are to build (although I'm sure Chris
Wilkson worked hard enough designing the CyberTech mod). Ben Heckendorn's
mod can probably be built by anyone with even minimal soldering
skills. Tackling the CD4050 mod is going to tax your patience,
unless you really, really, like to solder. Hand-wiring
one of these is pretty tedious, and not for beginners. (It's not
really that complex of a circuit - but if you don't have experience
with soldering, it's going to be frustrating.)

I'm not going to describe how to get an
Atari apart. If you can't get that far on your own, a video mod
is probably not a good idea. The CyberTech mod comes with detailed
instructions, but be sure to read them carefully - it's easy to
overlook steps.

Each mod requires picking signals off of
the TIA chip, and/or off the circuit board. There are schematics
for each scratch-built mod available at the links above. If you decide to build a CD4050
mod, there's a diagram of S-Video pin-outs available
here.

For the CyberTech mod, it uses an intermediate
socket to pull the signals off the TIA chip, so you don't have
to solder anything to the 2600 itself. It also includes the necessary
cables and wiring information. I've detailed
my experience with the CyberTech mod on this page. (Alternately,
you can pay extra to have Atari2600.com install the mod for you.)

Six-Switch model:

This shows the layout of a six-switch board,
and where to find the various connection points. The TIA is the
large, socketed chip at the bottom. Close-ups are below.

The cartridge slot is near
the top of this picture.

Close-up of the Audio and Chroma locations:

Attach to the leads highlighted
in blue.

Close-up of the +5 volts location:

This ground is on the underside
of the circuit board. There's a nice, big area there to solder
onto, but any common ground will work.

Close-up of the Luma and Sync locations:

The numbers above are the
TIA pins, which the mods will refer to.

Four-Switch model:

This shows the layout of a four-switch board,
and where to find the various connection points. The TIA is the
large, socketed chip at the bottom. Close-ups are below.

The cartridge slot is near
the top of this picture.

Close-up of the various signal locations:

Ground can be attached
at any common ground location.

Close-up of the +5 volts location:

Not all mods require power,
but here it is in case you need it.

Audio:

The 2600 was originally designed to have
two built-in speakers, and supposedly stereo sound (now you know
what those round vents are for in the top). Even though that was
abandoned, Rob Mitchell pointed out to me that you can separate
out the two audio channels on TIA pins 12 and 13, and get "stereo"
audio (although originally games weren't designed to take advantage
of this, some recent homebrew carts like SynthCart
and Skeleton
do). However, for the scratch-built mods, this involves bending
up those two pins on the TIA and soldering directly to them, which
isn't something I wanted to do, so I just went with mono audio,
which was easier. The CyberTech mod has stereo audio by default.

The most direct way to make an audio mod
is to connect the Audio point shown in the above pictures to the
center pin of an RCA connector, and then connect the 2600's ground
to the RCA's outer sleeve. Alternately, you could just build the
audio portion of the
CD4050 mod, which is the same thing, with the addition of
a capacitor as a filter.

General observations:

RF looks terrible on some games, not as
bad on others. RF through an adapter looks a little better than
with a switchbox. The noise that a switchbox picks up can be terrible,
although some contact cleaner can help.
Replacing it with an adapter (and a decent A/B switch from Radio
Shack) reduces noise and image artifacts, and is the simplest
upgrade you can make.

Composite video, whether through an adapter
or straight from a mod, suffers from dot crawl - fuzzy edges along
some horizontal areas of the picture. Depending on how good your
TV is, you may or may not be bothered by it. The only way around
this is by using S-Video.

S-Video looks best, by far. The images are
crisp and there's very little color bleeding. There's no dot crawl,
and the images have clarity rivaling that of a computer.

I used a calibrated Sony professional monitor
for all of the tests (a PVM-14M2U). For some tests, I had to run
the signal through an S-VHS VCR in order to get a stable image.
If the video signal is unstable, a VCR can stabilize the signal
enough for the monitor to achieve proper sync. If you build a
mod and it doesn't seem to be working, try running it through
a VCR.

The testing process - setup:

The picture below shows the setup I used
for testing with the six-switch 2600. The circuit board is resting
on top of the metal shield that's usually enclosing it. I put
a foam pad under the board, so nothing would short. This allowed
me to work on everything "right-side-up".

Somewhere in there, is
an Atari 2600...

In order to not damage my 2600 I didn't
solder anything to the circuit board. Rather, I used little copper
clips (available from Radio Shack) to hook onto the ends of resistors.
If you're building a mod for a permanent installation, you'll
need to solder instead. But this is a good way to test everything
before committing to it.

The blue stuff is electrical
tape, to keep the clips from contacting each other.

When permanently installing a mod, I'd suggest
soldering to the resistor leads, instead of trying to solder directly
to the TIA socket pins on the bottom of the board. For one thing,
there's less chance of damaging the TIA, but perhaps more important
- It's makes soldering easier, since you can hook the wires around
the resistor leads before soldering them on. Since these are directly
connected to the TIA pins, it makes no difference where you make
the connection.

To speed up testing, I used a terminal strip
to attach all of the necessary leads from the Atari 2600. These
include luma outputs, sync, chroma, audio, ground and +5 volts.
Then, I could just hook up each mod to the terminals, without
having to connect new clips to the circuit board.

I also made a small video/audio interface
board, with screw terminals on it, for the same purpose. That
allowed me to always leave my audio/video connections hooked up,
and just swap out the mods.

That's the S-Video connector
on top. Composite video and audio are below it.

The mods were tested with S-Video, if it
worked. If not, composite video was used. As a reference, RF was
also tested, since this is how the Atari was designed to output
signals. (The first round of tests for this site were composite-only,
because I couldn't get S-Video to work at the time. Since then,
I've gotten it to work thanks to a little help from Rob Mitchell,
and all current results reflect this.)

RF signals were routed through an S-VHS
VCR, using its S-Video output. Chris Cracknell's mod and Ben Heckendorn's
mod were also run through the S-VHS deck (using composite in and
out), since the signal was too weak without it to get a stable
signal. This depends largely on how forgiving your TV or video
monitor is with unstable signals, so you may not require a VCR.

The testing process - procedure:

First, I let the system being tested warm
up. I've found that the colors shift after awhile, if the unit
has been left off. Then, I used the Color Bar Generator's title
screen to calibrate the color using the big potentiometer on the
main board - basing the adjustments on the instructions for that
cart (which can be viewed
at AtariAge).

"The color phase angles are generated
by delaying the color signal until the desired phase angle is
selected. An adjustment potentiometer is placed on the VCS console
circuit board to adjust the 360 degree delay so that it is the
same as 0 degrees. Although we do not recommend that you void
any warranty on your game console, the potentiometer (the only
one) can be adjusted so that the top half of the colored box
is as close to the same color as the bottom half. The color generation
circuits can then correctly produce colors from 0 to 360 degrees."

Six-switch color adjustment:

When adjusting this potentiometer, use a small screwdriver in
the center.
It's easier to make fine adjustments than if you just grabbed
it with your fingers.

Four-switch color adjustment:

You can also adjust these
through the hole located on the bottom side of the board.

I figured this would give the best idea
of which video mod was interpreting the color signals most accurately.
That way, I'm testing how each mod works, rather than using the
2600 to compensate for each mod, or adjusting the video monitor
until it looks good. (Ben's mod required some additional back-and-forth
adjustments, since his mod uses two potentiometers for adjustment.
The CyberTech mod allows for adjustment of the picture, but it
isn't required to get it to work.)

Once the color was calibrated to that reference,
I'd test various carts, and recorded the signal onto a Sony DSR-25
DVCAM VTR. This is about the equivalent of digitizing using a
DV converter, except it has better image quality than a consumer
setup. I then did a direct FireWire transfer of the video into
Final Cut Pro, so there was no signal loss from the digital tape.
Finally, I used After Effects to pull individual frames from the
captured video, and saved them as uncompressed PNGs. Even though
DV does use compression for video, there were no noticeable artifacts
from the compression present in any of these tests, since there
was very little movement happening onscreen.

Below are the carts I tested, listing the
still frames I've taken from the captured video. They've been
left at 720x480, and interlaced, so it looks the way it does on
an NTSC monitor. I've made notes of why I chose these particular
screens for comparison.

Game
name / screen

Notes

Picture

Color
Bar Generator
title screen

Color phase
calibration - the top and bottom of the greenish border should
match

In the original series of tests
for this page, I included more games, including Tac/Scan, Pitfall,
Centipede and Crystal Castles. However, I felt some of them were
poor examples or redundant, so I opted for these instead. This
should give a good enough cross section to show the differences
in image quality under various conditions.

Test results:

Depending on your particular TV or video
monitor, you may have better or worse results. Some monitors are
more forgiving with unstable video signals than others. For a
couple of the mods, I had to run them through a VCR to stabilize
the signal.

There's some ghosting on the images (which
appear as faint double images to the left or right), but all of
the video mods and RF output exhibit this, and it's more likely
something to do with the TIA itself, than something that can be
eliminated. It's less noticeable on an NTSC monitor than it is
in these screen captures.

The video driver
- For the life of me, I couldn't get it to work on either 2600
or my 7800. I tried various connection points on the 2600s and
7800, double-checked the diagram, and even changed the circuit
once to account for a possible ambiguity in the diagram. All I
got was a brief "blink" on the NTSC monitor when I powered
up, then black, so no test results are available. I'd be very
interested in hearing from anyone who has gotten this to work,
and could shed some light on the matter.

Chris Cracknell's mod - This is where everything is crunched together
with no additional components. Without running it through a VCR,
most games would start up very bright, then rapidly fade to almost
nothing within seconds. On other games, the brightness fluctuated
a lot, and the image was very unstable. Running it through a VCR
helped, but some games lacked color, others had large areas of
color flaring across the screen, and nothing was really what I
would call acceptable.

RF video - The
default video of the 2600, which you've been looking at for over
20 years. It doesn't look too bad, until you have something better
to compare it with - then you start seeing how awful it really
is. Indistinct shapes, soft edges, dull colors, and plenty of
noise mar the picture. The plus side is that it's easy to hook
up. A direct adapter gives a better picture than a switchbox,
but unless you want to live without cable or satellite, you'll
have to get some sort of switch for it. If you must use the old
switchbox, hit it with some contact cleaner.

A note regarding contact cleaner: I've
been told that Radio Shack's cleaner can gum up over time, so
I'd avoid theirs. I've had good luck using this
cleaner. Rubbing alcohol is another option. (Thanks to sku_u
for the info.)

Ben Heckendorn's mod - For being so simple, it works remarkably well.
Initially, the video was extremely unstable on my monitor, which
resulted in a very dark and wobbly image. However, by running
it through a VCR, the image stabilized, and the picture looked
very good and quite bright. (Depending on your particular monitor,
you may or may not need to run the signal through a VCR first.)
The mod requires some tweaking of the two potentiometers on the
mod and the one on the 2600 to get decent colors, which may be
hard to do without a test cart. This mod didn't work at all with
an S-Video connection - the image would distort to the point of
being unrecognizable. Still, it has a good composite picture,
it's easy and cheap to build, and may suit most people's needs
just fine.

The CD4050 mod w/out the CD4050 - The exact same circuit as the CD4050 mod, but
I removed the CD4050 from its socket, and put jumpers in its place.
It worked nearly as well as the CD4050 circuit, but it was slightly
darker (see next paragraph). You might consider this if you want
a good picture, with a little less work than the CD4050 requires
to build.

The CD4050 mod
- Worked very well, and had the closest colors to the RF connection.
Somewhat dimmer than Ben Heckendorn's or the CyberTech mod, but
a very good S-Video picture. Takes about $20 in parts and a lot
of effort to build, though. A good project for the do-it-yourself
enthusiast.

The CyberTech mod - Easily the best of the bunch, and the one that now
permanently resides in my six-switch 2600. It's the easiest mod
to install (despite the issues I ran
into), and produces a beautiful, clean, bright S-Video picture.
The only downside to this mod is the cost - $59.95 plus shipping
is pretty steep. But after the work I put into the CD4050, I found
it worth the money. You can also have Atari2600.com install it
in your 2600 for $84.95, but I don't think it's worth that kind
of money. If you can't install it yourself, you'll be better off
finding a friend or neighbor with a soldering iron. A couple of
pluses are 1) it's completely reversible if you want to remove
it and 2) it has "stereo" sound. Admittedly, stereo
works better on some games than others, but it's a nice extra.
(The 2600 has two sound channels, and one gets sent to each speaker,
but it's not true "stereo" since the use of the channels
tends to be arbitrary.) The CyberTech mod also allows you to adjust
brightness, contrast and saturation. I discovered after the first
round of tests that I needed to adjust
the saturation, so there are two sets of test results shown
below - the first set is from the mod as preset by the manufacturer,
and the other set is after I adjusted it.

Captured images:

These are all maximum quality JPEG files, so there's
almost no additional image compression beyond the DV compression used
during capture. (For what it's worth - these are very accurate
representations of what was on the NTSC monitor. I switched back
and forth between a live image from the 2600 and the captured
video to be sure I wasn't picking up unwanted artifacts.) They're
listed approximately in order of increasing image quality, from
least to highest.

The frame captures shown here tend to exaggerate
some of the ghosting that happens in the picture (noticeable on
the trees in Pitfall II, and on the vertical lines in Midnight
Magic), in part because the computer can capture a much wider
range of picture information than most NTSC monitors will display.
Also, DV uses non-square pixels, which exaggerates the width of
the images. While these color artifacts are still visible to a
degree on a real 2600, they're far less noticeable on an NTSC
monitor due to the limited color space, and the presence of scanlines.

Click on a thumbnail to view the full-sized
image.

Some
of these are large files, up to 200 KB.
I'm just making a list of what's available, so you can open them
for yourselves and compare what you wish.

S-Video to composite video adapter results:

I used the preset CyberTech mod for these
tests, running the S-Video out through each adapter. One was an
adapter I bought at Roger's
Systems Specialists for $5 (similar ones are available elsewhere),
and the other was a $100 adapter from Monster Cable, which is
apparently no longer manufactured. The point of this comparison
is to show the difference between S-Video and composite video,
and also that you don't need an expensive adapter to get the same
results. (However, going from composite video to S-Video is an
entirely different matter.)

I did not test the do-it-yourself adapter
shown on
this page. I'll try to add it in a future update.

In conclusion (for now):

As I have the time, and as I'm made aware
of new mods or kits, I'll test them out and post the results here.
Hopefully this will be of use to people. There's probably no single
solution that applies to everyone, since everyone has different
skill levels, budgets, and opinions. For my money, the CyberTech
mod won out, although if I were on a tight budget, I would probably
have been just fine with Ben Heckendorn's. Almost anything is
better than the 2600's built-in RF.